The Rochester Developmental Psychopathology Study aims to clarify the relationships among organic and environmental factors in the formation of serious mental disorder. Maternal psychiatric diagnosis: chronicity of illness; social competency; anxiety level; attitudes toward pregnancy and childrearing; and, socioeconomic status have all been indexed. Critical intellectual and social adjustment dimensions of children have also been chosen to establish the linkages between maternal behavior and children's development. Data has been collected both pre-natally and at five periods during the early life of the child, - birth; four months; 12 months; 30 months; and 48 months. This longitudinal program has begun to allow a more refined description of the complex interaction between constitutional and social factors in the evolution of psychiatric disability.